Institute of Cosmology and Gravitation

  • Home
  • News
    • Positions available
  • ICG Members
    • ICG Academic Staff
    • ICG Professional and Support Staff
    • ICG Research Staff
    • ICG Students
  • For The Public
    • New to Cosmology?
    • Upcoming Events
    • Schools Outreach
    • Outreach Resources
      • Cosmic Stroll
    • Research Experience
    • Athena SWAN @ ICG
    • Dignity & Respect
  • Research Overview
    • The Very Early Universe
    • Dark Energy
    • Late-time Acceleration
    • Large Scale Structure
    • Relativistic Cosmology
    • Gravitational Lensing
    • Transients
    • Galaxy Evolution
    • Stellar Population Modelling
    • Gravitational Waves
  • Talks, Lectures, Meetings
    • Colloquia
    • Tuesday Lunch
    • Theoretical Cosmology
    • Lectures
    • Galaxy Breakfast
    • LSS Meetings
    • Lensing Meetings
    • Gravity Meetings
    • UoP Workshops
    • GRADnet
  • Study With Us
    • Physics@Portsmouth
    • SEPnet
    • DISCnet
  • Contact Us

Gravitational Lensing

As light flies through the Universe, we might suppose that it will travel along a straight line. This turns out not to be the case: light rays can be bent by the effects of gravity in the Universe. Wherever there is a clump of matter, there is a slight gravitational distortion of space and time; the light that passes near such a clump will therefore be deflected. We call this bending of light “Gravitational Lensing”.

Gravitational lensing by a cluster of galaxies. The large arc-like objects are galaxy images which have been severely gravitationally lensed.

Gravitational lensing by a cluster of galaxies. The large arc-like objects are galaxy images which have been severely gravitationally lensed. Credit: NASA, ESA, the Hubble SM4 ERO Team, and ST-ECF

This leads to striking images of distant galaxies, where their appearance has been stretched and magnified by gravitational lensing. In the most extreme cases multiple images of a single background source are observed. These ‘strong’ gravitationally lenses are very rare, requiring alignments to within 1/3600th of a degree. ‘Weak’ lensing is common: every distant source is distorted slightly as it travels through our inhomogeneous Universe.

ICG researchers are using both strong and weak lensing to study the objects causing the gravitational lensing, the expansion of the Universe, and the behaviour of gravity itself.

A Horseshoe Einstein Ring from Hubble.JPG

The cosmic horseshoe gravitational lens, as observed by the Hubble Space Telescope. The mass of the orange galaxy distorts space-time so much that a single blue galaxy appears as the blue ring. (credit NASA/ESA)

ICG staff working in this field include:

Professor Adam Amara

Professor David Bacon

Doctor Thomas Collett

promo-button-public1promo-button-partners11promo-button-members1

Latest News

  • Project to help vision impaired people engage with astronomy wins award
  • Bumper crop of black holes in new gravitational wave paper
  • Major EU grant to unravel the mysteries of the Universe
  • Ripples from deep in the Cosmos reveal most massive black hole detected yet
  • Astrophysicists fill in 11 billion years of Universe history.

Coming up

  • Anut Sangka on January 19, 2021 12:00 pm
  • Wentao Luo (IPMU, Japan) on January 20, 2021 1:00 pm
  • Galaxy breakfast on January 21, 2021 12:00 pm
  • Kate Maguire (TCD), TBA on January 21, 2021 2:30 pm
  • Science Chat on January 22, 2021 11:00 am

Quick Links

  • How to get to the ICG
  • Upcoming Events
  • Additional Links

Twitter

Tweets by @UoPCosmology

Facebook

Design by FingerprintDigitalMedia.com
Copyright © 2021 ICG, Portsmouth

Institute of Cosmology and Gravitation Cookies Policy

Our Website uses cookies to improve your experience. Please visit our Cookies and privacy page for more information about cookies and how we use them.

Close